In a storage device, a solid-state drive (SSD) is a new-type storage device that is based on a semiconductor solid-state memory technology. The SSD has advantages, such as a high read/write speed, high shock resistance, a large temperature range, a small volume, and a light weight, over a conventional mechanical hard disk.
In general, a write operation performed by a host device on the SSD has two modes: a write-through mode and a write-back mode. A speed of the write-back mode is typically higher than that of the write-through mode. However, in the write-back mode, the SSD first writes data in a buffer of the SSD, and then returns a message indicating a write success to the host device, and the host device considers that the SSD has completed data storage. Then, a main control chip of the SSD flushes the data to a back-end flash memory chip of the SSD. If a platter of the SSD is powered off in this case, data in the buffer will be lost. Therefore, in SSD design, usually a backup power circuit is added. The backup power circuit includes some capacitors that are coupled in parallel. One end of each of the some capacitors is coupled between an input end and an output end of the backup power circuit, and the other end is grounded. The backup power circuit is used to provide the SSD with the electric energy required, when unexpected power-off occurs, for flushing the data in the buffer to the flash memory chip, so as to avoid a data loss.
However, because the capacitors in the backup power circuit are coupled in parallel, if one of the capacitors is short-circuited, the entire backup power circuit fails, thereby affecting a backup power effect of the backup power circuit.